Load-landing device

ABSTRACT

A load-landing device wherein a load-carrying plate dropped from an aircraft carries underneath its lower surface substantially frustoconical inflatable bags which are carried in their turn by an intermediate plate provided with perforations through which the bags communicate with the inside of skirts depending from the intermediate plate. Thus when the device is dropped, the volume confined within the skirts is fed with air out of the bags so that the cushions formed within said confined volumes sustain the device and allow it to move over the ground as long as it has not collapsed completely, after which it can progress over the shoes incorporated with it.

llnite States Patent 2,774,560 12/1956 Johnson Inventors Paul FrancoisGuienne Paris; Paul Aime Lebargy, Les Clayes-sous-Bois, both of FranceAppl. No. 868,018 Filed Oct. 21, 1969 Patented Dec. 7, 1971 AssigneeBERTIN & Cie

T IFsh France Priority Oct. 23, 1968 France 171003 LOAD-LANDING DEVICE 7Claims, 11 Drawing Figs.

US. Cl 244/138 R llnt. Cl 864d 1/08 Field of Search 244/ 100, l 3 8; l 88/ l 5 References Cited UNITED STATES PATENTS Primary Examiner-MiltonBuchler Assistant E.raminer- Paul E. Sauberer Attorney-Stevens, Davis,Miller & Mosher ABSTRACT: A load-landing device wherein a load-carryingplate dropped from an aircraft carries underneath its lower surfacesubstantially frustoconical inflatable bags which are carried in theirturn by an intermediate plate provided with perforations through whichthe bags communicate with the inside of skirts depending from theintermediate plate. Thus when the device is dropped, the volume confinedwithin the skirts is fed with air out of the bags so that the cushionsformed within said confined volumes sustain the device and allow it tomove over the ground as long as it has not collapsed completely, afterwhich it can progress over the shoes incorporated with it.

'PATENTED nE-c new 3.625451 SHEET 2 UF 3 PATENIEMEE m. 3525461 SHEET 3BF 3 LOAD-LANDING msvrcr:

In the US. Pat. No. 3,266,757 a device is described which is designed soas to damp the impact on a landing surface, such as the ground, of aload the downward speed of which has a vertical component of a fewmeters per second, this being in particular the case of a load releasedwith a parachute or else at a low altitude without a parachute, thisdevice cutting out the danger of a frictional contact with the groundleading to a turning round of said load. In said prior arrangement theplate carrying the load was provided with bags formed each by adeformable fluidtight wall connected on the one hand with said carrierplate and on the other hand with an intermediate plate or board thelower surface of which carries skirts defining with the ground chambersor spaces communicating with the corresponding bags through portsprovided in said intermediate plate.

According to a particular feature of said device, any horizontal crosssection of the bag has an area which is smaller than any horizontalcross section of the associated skirt.

Such a feature allows a preferential crushing of the bags rather than ofthe skirts to be obtained upon impact with the ground so that the fluidcontained in said bags may escape into the sustaining fluid cushions inthe skirts through the communication ports in the intermediate plate.The cross sections of the ports affording a passageway are gauged in amanner such that the pressure prevailing in the bag may rise up to avalue sufficient for the desired vertical deceleration to be ensured.

Now according to our present invention, the coefficient of loss of headin the communication ports is such that, in an embodiment of the deviceincluding frustoconical or the like bags over also frustoconicalconfining spaces and for each of such a combination of a bag andconfining space, the following is true:

s being the total area of the gauged ports S the area of the openingdefined by the free lower edge of the skirt D the diameter oflast-mentioned area h the height of the leak gap under the skirts S thearea of the larger base of the frustocone defined by the bag.

According to a further feature of our invention, the arrangement of thebags and their shape allow the lateral relative movements of the platecarrying the load with reference to the intermediate plate to belimited. The axes of said bags which are for instance substantiallycylindrical are parallel with the carrier plate or with the intermediateplate or again the bags may assume the shape of volumes the bases ofwhich are defined by sections of a straight line extending insubstantial parallelism and connected with each other by arcs of acircle the vertical transverse cross sections of said volumes assumingsubstantially the shape of isosceles trapeziums.

According to further features of our invention, the arrangement includesmeans for improving the expansion of the bags and possibly of thefluid-containing spaces within the skirts during the dropping of theload. Said means may be constituted by elastic members which arecompressed as long as the intermediate plate is near the carrier plateor else by weights or fairings connected with the intermediate plate orwith the confining shirts by gauged connecting members in a manner suchthat said different members break when the device is released after thebags have expanded.

In the accompanying drawings given by way of example:

F IG. 1 is a diagrammatic elevational view of a device incorporating theimprovements according to the invention;

FIG. 2 is a cross section through line II-II of FIG. 1, on which theload has not been illustrated and which shows the condition of the bagsbefore the impact with the landing surface;

FIG. 3 is a view similar to FIG. 2 illustrating the beginning of thestage during which the speed of descent of the load is braked and thedevice can move over cushions of a compressed fluid;

FIG. 4 is a view similar to FIG. 2, illustrating the end of thespeed-damping stage;

FIGS. 5 and 6 are respectively a partial view similar to FIG. 2 and apartial view similar to FIG. 1, illustrating the engage ment of thedevice over the landing area through the agency of shoes;

FIG. 7 is a diagrammatic view from above of an embodiment of the devicethe carrier plate of which is not illustrated;

FIG. 8 is a partial sectional view through line VIII-VIII of FIG. 7;

FIG. 9 is a partial view similar to FIG. 8 showing modifications in thebags;

FIGS. 10 and 11 are views similar to FIG. 7 showing other arrangementsfor the bags.

Turning to FIGS. 1 to 6, the latter show a device including aload-carrying plate 1 underneath which there extends an intermediateplate or board 31 while bags 32 are fitted between the two plates 1 and31 and skirts 33 secured to the lower surface of the intermediate plateare directed towards the landing surface 34 on the ground. The bags andskirts may be executed for instance by means of a fabric covered by afluidtight coat which is impervious for the fluid used and which may beconstituted by a mixture having a base rubber or an elastomer. The shapeof said bags and skirts may vary, but it is advantageously ofrevolution. The bags are advantageously of a substantially frustoconicalshape, their larger base being rigid with the intermediate plate 31.Obviously however our invention is applicable as well with bags theshape of which is different and is for instance that of a section of aprism or a frustopyramid. The skirts 33 are advantageously frustoconicaland stand in substantial coaxial relationship with the bags. Theirlarger upper base is also secured to said intermediate plate.

As more particularly apparent from inspection of FIG. 2, any crosssection of a bag 32 is smaller than any cross section of the confiningvolume enclosed by the associated skirt 33. In other words, if S is thecross section of the smaller base of the frustocone defined by the skirt33 and S, the cross section of the larger base of the frustocone definedby the corresponding bag it is possible to write down The spaces in thebags 32 and the volume enclosed by the skirts 33 communicate throughopenings 35 formed in the intermediate plate 31 is provided by a plate36 showing ports 37 having a gauged cross section s2, the sum s of saidcross sections being defined as a function of the weight of the load, ofits speed of impact on the ground and of its desired verticaldeceleration. However the coefficient defining the loss of head in thegauged ports 37 should be such that in each system including afrustoconical bag 32 and a frustoconical skirt 33 the following formulais satisfied where s is the total area of the gauged ports 37 (S=Zs2) S,the area of the circular bearing surface of the cushion defined by thefree edge of the skirt 33 resting on the landing surface 34 D thediameter of said surface (s=(11'D )/(4) h the height of the leak gapleft free by the skirt 33 over the landing surface 34 S the area of thelarger base of the frustocone defined by by the bags 32.

The plate 36 may be removable whereby it is possible to select one ofseveral such plates in which the sum s of the cross sections of thegauged ports 37 satisfies various conditions of operation as concernsthe load, the speed of approach of the load towards the landing surfaceand the like, This makes it easier to adjust the coefficient of loss ofpressure.

The expansion of the bags 32 and skirts 33 is obtained by reason of theactual weight of the device during the dropping of the latter. Theintermediate plate 31 may also be connected through gauged connectingmembers 38 with a fairing such as 39 (FIG. 1). Said fairing encloses allthe parts located underneath the plate 1 when the device is positionedon board an aircraft. When the device is released, the fairing 31carries along with it towards the landing surface the intermediate plate31, the carrier plate 1 being braked by the parachute. After expansionof the bags 32 the tensioning of the connecting members 38 rises beyondtheir breaking limit, which separates the fairing 39 from the remainderof the device.

If the time interval elapsing between the release of the device and theimpact of the latter on the landing surface is small, more particularlyin the case of a release of the load without any parachute off anaircraft flying at a low altitude auxiliary means may be resorted to. Byway of example and as illustrated in FIG. 9, elastic members 50 may beinserted between the cooperating surfaces of the carrier plate 1 and ofthe intermediate plate 31 within the bags for instance. The deviceillustrated includes shoes 41 extending advantageously throughout thelength of the underside of the carrier plate I. Said shoes 41 aresecured to either side of the longitudinal axis of the device throughthe agency of the arms 42 which are rigid in their turn with theperiphery of the carrier plate 1. The length of said arms 42 is suchthat the shoes engage the landing surface 34 only when the bags 32 andpossibly the skirts 33 when no longer fed with fluid under pressure,have been sufficiently crushed as illustrated in FIGS. and 6 as aconsequence of the exhaust of the fluid contained in the bags 32 andskirts 33, that is when no progression of the device can any longer beprovided over cushions of compressed fluid. Said shoes further then thedesired sliding movement of the device over the landing surface. Saidshoes as apparent from inspection of the drawings are spaced withreference to the carrier plate 1 whereby the basis of the support isincreased and the risks of turning over are reduced.

As apparent from FIGS. 7 to 11, the arrangement of the bags 32 and alsotheir shape provides a limitation of the relative lateral movements ofthe carrier plate 1 with reference to the intermediate plate 31.

The bags 32 may be constituted by envelopes 43 closed at their ends andthe shape of which is substantially cylindrical with an axis parallelwith the carrier plate 1 and/or the intermediate plate 31 as illustratedin FIG. 8. The bags may also be given the shape of the volume 44illustrated in FIG. 9, the bases of which are defined by sections of astraight line which are substantially parallel and interconnected byarcs of a circle, the vertical cross sections of said volume beingsubstantially in the shape of an isosceles trapezium.

A number of the bags may be arranged in a manner such that theirlongitudinal planes cut one another. Thus the bags may be arranged insubstantial parallelism with all sides of the carrier plate 1 and/or ofthe intermediate plate 31.

Said bags may be distributed in a substantially symmetrical relationshipwith reference to the medial planes of the plates 1 and 31 as clearlyshown in FIG. 7.

The bags may be advantageously distributed symmetrically with referenceto an axis which is substantially perpendicular to the carrier plate 1and/or to the intermediate plate 31. As also illustrated in FIGS. and11, the longitudinal plane perpendicular to the carrier plate 1 and/orto the intermediate plate 31 of each of the bags may also extend throughthe volume defined by the adjacent bag.

It is possible to arrange bags of a substantially equal length inassociation with plates of a substantially square shape (FIG. 10) orelse bags of unequal lengths in association with plates of any desiredshape whatever as illustrated in FIG. 11.

The operation of the device is as follows:

Assuming it is dropped by an aircraft with or without a parachute (FIG.1), the expansion of the bags and skirts is ensured by the partsdescribed hereinabove. At the moment of the impact on the landingsurface 34 (FIG. 3) and in accordance with the features of our inventionthe bags 32 are deformed before the skirts 33 in a manner such that thefluid carried in said bags escapes into the supporting cushions withinthe confining skirts. Said deformation has for its result a reduction inthe inner volume of the bags and an increase in the pressure of thefluid carried in the bags, this depending quantitatively on the crosssection of the gauged ports 37 forming passageways and leading to theobtention of the desired vertical deceleration. Throughout duration ofthe crushing of the bags, the device is adapted to move over thecushions of compressed fluid, which latter are formed in the skirts 33and are fed by the fluid under pressure passing out of the gauged ports37. As soon as the bags have been completely crushed and the skirts 33are partly crushed because they are no longer fed with fluid undersufficient pressure, at such a moment the shoes 41 carry the device overthe landing surface 34 which allows the device to continue if requiredits movement over said landing surface (FIGS. 5 and 6).

The material forming the intermediate plate 31 may show a sufficientyieldingness so as to absorb readily the stresses produced at the momentof the impact of the device on the landing surface 34 if the device isthen not perfectly parallel with said surface. This is particularly thecase when the load is released off an aircraft flying at a low altitude.

The intermediate plate 31 may be made for instance of veneer or of athermoplastic material such as polyethylene.

We claim:

1. A load-landing device adapted to be released off an aircraft,comprising a load-carrying plate, at least one yielding substantiallyfrustoconical fluid-containing bag fitted underneath the plate, ayielding substantially frustoconical fluidconfining skirt carriedunderneath and in vertical registry with each bag and terminating at itslower end with a free circular edge, throttled passageways connectingthe inside of the skirt with the corresponding bag, the followingunequalities being satisfied:

s being the total cross-sectional area of the gauged ports connectingthe bag and corresponding skirt S the cross-sectional area defined bythe said free circular edge of the skirt D the diameter of said circularedge h the height of the leak gap between the circular edge and thesurface on which the device is dropped upon landing, which height ispredetermined for a given load S the area of the larger base of thefrustoconical bag.

2. A device as claimed in claim 1 comprising an intermediate plateextending underneath the bags and over the skirts and provided with alarge opening between each bag and the corresponding skirt and anauxiliary removable plate covering each opening and incorporating thepassageways connecting said bag with the inside of the correspondingskirt.

3. A device as claimed in claim 1 comprising an intermediate plateextending underneath the bags and over the skirts and incorporatingpassageways connecting said bags with the inside of the correspondingskirts and elastic members inserted between the load-supporting plateand the intermediate plate and urging said plates apart to further theexpansion of the bags during the dropping of the device.

4. A device as claimed in claim 1 comprising an intermediate plateextending underneath the bags and over the skirts and incorporating thepassageways connecting said bags with the inside of the correspondingskirts and elastic members inserted between the load-supporting plateand the intermediate plate and through each bag and urging said platesapart to further the expansion of the bags during the dropping of thedevice.

5. A device as claimed in claim 1, provided with a parachute, comprisinga weight, gauged members securing said weight underneath the other partsof the device and adapted to break under a predetermined tensionalstress while the device is being dropped and decelerated by itsparachute.

6. A device as claimed in claim 1 provided with a parachute comprising aheavy fairing carrying and enclosing when at rest the other parts of thedevice, gauged members holding said fairing in position underneath saidother parts during the dropping of the device and adapted to break undera predetermined tensional stress while the device is being dropped anddecelerated by its parachute.

7. A device as claimed in claim 1, provided with a

1. A load-landing device adapted to be released off an aircraft,comprising a load-carrying plate, at least one yielding substantiallyfrustoconical fluid-containing bag fitted underneath the plate, ayielding substantially frustoconical fluid-confining skirt carriedunderneath and in vertical registry with each bag and terminating at itslower end with a free circular edge, throttled passageways connectingthe inside of the skirt with the corresponding bag, the followingunequalities being satisfied: and S>S1 s being the total cross-sectionalarea of the gauged ports connecting the bag and corresponding skirt Sthe cross-sectional area defined by the said free circular edge of theskirt D the diameter of said circular edge h the height of the leak gapbetween the circular edge and the surface on which the device is droppedupon landing, which height is predetermined for a given load S1 the areaof the larger base of the frustoconical bag.
 2. A device As claimed inclaim 1 comprising an intermediate plate extending underneath the bagsand over the skirts and provided with a large opening between each bagand the corresponding skirt and an auxiliary removable plate coveringeach opening and incorporating the passageways connecting said bag withthe inside of the corresponding skirt.
 3. A device as claimed in claim 1comprising an intermediate plate extending underneath the bags and overthe skirts and incorporating passageways connecting said bags with theinside of the corresponding skirts and elastic members inserted betweenthe load-supporting plate and the intermediate plate and urging saidplates apart to further the expansion of the bags during the dropping ofthe device.
 4. A device as claimed in claim 1 comprising an intermediateplate extending underneath the bags and over the skirts andincorporating the passageways connecting said bags with the inside ofthe corresponding skirts and elastic members inserted between theload-supporting plate and the intermediate plate and through each bagand urging said plates apart to further the expansion of the bags duringthe dropping of the device.
 5. A device as claimed in claim 1, providedwith a parachute, comprising a weight, gauged members securing saidweight underneath the other parts of the device and adapted to breakunder a predetermined tensional stress while the device is being droppedand decelerated by its parachute.
 6. A device as claimed in claim 1provided with a parachute comprising a heavy fairing carrying andenclosing when at rest the other parts of the device, gauged membersholding said fairing in position underneath said other parts during thedropping of the device and adapted to break under a predeterminedtensional stress while the device is being dropped and decelerated byits parachute.
 7. A device as claimed in claim 1, provided with aparachute, comprising an intermediate plate extending underneath thebags and over the skirts and incorporating the passageways connectingsaid bags with the inside of the corresponding skirts, a fairingcarrying and enclosing when at rest the other parts of the device, andgauged members securing the fairing to the intermediate plate to hold itin position underneath said other parts during the dropping of thedevice and adapted to break under a predetermined tensional stress whilethe device is being dropped and decelerated by its parachute.